Hardly any traces remain of a town called Moncton which existed at the northern edge of Rattlesnake Lake from 1906-1915.
The City of Seattle began building a dam in 1914 on the Cedar River, right between Cedar Lake and Rattlesnake Lake. The dam was meant to generate electric power for City Light. There was a big problem though, the entire dam was built on top of a giant glacial moraine. This meant it was ultimately going to leak water like a sponge. Residents at the time began noticing lots of mini-geysers erupting from the hills above Moncton. All the extra water had nowhere to flow but right into Rattlesnake Lake. The lake slowly began to rise. Within days the streets were completely muddied and it is said that in the month of May 1915 water began rising a little over a foot per day. Rowboats were floated in to help remove furnishings and personal belongings that could still be salvaged. Ultimately the City of Seattle condemned the town of Moncton and residents were paid for the damages to their land and homes. Again, very few traces remain of the forgotten town. It’s only when the water recedes enough during summer months that brick foundations from the original town are exposed and can still be seen today.